database

database.go

@@ -0,0 +1,71 @@
+package main
+
+import (
+"net"
+"fmt"
+"os"
+"strings"
+)
+
+type DatabaseServer struct {
+	port uint16
+	store map[string]string
+}
+
+func NewDatabaseServer(port uint16) *DatabaseServer {
+	return &DatabaseServer{
+		port,
+		make(map[string]string),
+	}
+}
+
+func (s *DatabaseServer) Run() {
+	addr := fmt.Sprintf("0.0.0.0:%d", s.port)
+	pc, err := net.ListenPacket("udp", addr)
+	if err != nil {
+		fmt.Println(err)
+		os.Exit(1)
+	}
+	defer pc.Close()
+	buf := make([]byte, 1000)
+	fmt.Println("Database server listening for packets")
+	for {
+		n, addr, err := pc.ReadFrom(buf)
+		if err != nil {
+			continue
+		}
+		s.handle(pc, addr, string(buf[:n]))
+	}	
+}
+
+func (s *DatabaseServer) handle(pc net.PacketConn, addr net.Addr, req string) {
+	var resp string
+	fmt.Printf(">> %s\n", req)
+	if strings.Contains(req, "=") {
+		s.handleInsert(req)
+	} else {
+		resp = s.handleRetrieve(req)
+	}
+	if resp != "" {
+		fmt.Printf("<< %s\n", resp)
+		pc.WriteTo([]byte(resp), addr)
+	}
+}
+
+func (s *DatabaseServer) handleInsert(req string) {
+	parts := strings.SplitAfterN(req, "=", 2)
+	key := strings.Trim(parts[0], "=")
+	value := parts[1]
+	if key == "version" {
+		return
+	}
+	s.store[key] = value
+}
+
+func (s *DatabaseServer) handleRetrieve(req string) string{
+	if req == "version" {
+		return "version=Deathstar planetary target database v2.9 build 73839"
+	}
+	value := s.store[req]
+	return fmt.Sprintf("%s=%s", req, value)
+}

main.go

@@ -12,7 +12,7 @@ type Server interface {
 	
 func main() {
 	var challenge int
-	flag.IntVar(&challenge, "challenge",3, "Challenge number")
+	flag.IntVar(&challenge, "challenge",4, "Challenge number")
 	flag.Parse()
 	
 	var port uint16 
@@ -27,6 +27,8 @@ func main() {
 	  	server = NewMeansServer(port);
 		case 3:
 	  	server = NewChatServer(port);
+		case 4:
+	  	server = NewDatabaseServer(port);
 		default:
 			fmt.Printf("Unknown challenge\n")
 			os.Exit(1)